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After a breast cancer diagnosis, you could be facing treatments that can affect your fertility, which can be devastating if you haven't completed your family.

Treatments for breast cancer can bring about early or ‘premature’ menopause (stopping menstrual cycles before your body would naturally), and so can cause temporary or permanent infertility. If you want to have children, discuss with your surgeon or oncologist how breast cancer treatments could affect your fertility before you start treatment.

If you’re going to have chemotherapy, a referral to a fertility clinic before treatment starts is essential, and will help you understand your options.

How do treatments affect fertility?

Everyone responds to treatment differently, so it can be hard to determine exactly how medical interventions will affect your fertility. However, the risk of permanent infertility from treatments is greatest for women aged over 35 years. Your periods may return, but menopause may come earlier than it would have if left to occur naturally.

Chemotherapy affects the functions of your ovaries, which means that fewer or no eggs are produced, and your periods could become irregular or stop altogether during chemotherapy. Chemotherapy damages blood vessels around the ovaries, and damages developing, immature eggs. Whether your periods and your fertility will recover depends on the type of chemotherapy used, the dosage, and your age at the start of treatment.Younger women who have a higher reserve of eggs in their ovaries are more likely to retain fertility but may experience menopause earlier than usual.

Your treatment may be able to be structured to optimise fertility preservation, if this is a priority for you. Some chemotherapy drugs may be less harmful to the ovaries and certain hormonal treatments may be given to try and protect your ovaries during treatment. There is also the option of preserving your fertility prior to treatment. Talking this through with your specialist team is essential.

Preserving your fertility before treatment starts

Here are some options to discuss with your specialist:

Freezing embryos
This process uses IVF (in-vitro fertilisation), and is the best method if you have a partner. Hormonal drugs are used to stimulate egg production, and the eggs are harvested, placed with sperm, and any resulting fertilised eggs (embryos) can be frozen.

Freezing eggs
This is suited to women who don’t have a partner. Egg production is stimulated by hormonal drugs, the eggs are harvested and frozen, and then can be thawed and fertilised with sperm in the future.

Both embryos and eggs can be stored for up to 10 years, and both of these options are government-funded in New Zealand for women who are aged under 40, have no children and have a body mass index of less than 32.

Both options require careful consideration for women diagnosed with breast cancer, as the IVF process might delay the start of cancer treatment.Where necessary a short protocol (12 days) can be administered with few side effects. Ovarian stimulation, which is used to increase the number of eggs available, raises the body’s level of systemic oestrogen, which can stimulate the growth of cancer cells but a short course of letrozole can be used to decrease this risk.

Freezing ovarian tissue
This technique involves a laparoscopic procedure where ovarian tissue is removed, sliced and frozen. The tissue can be put back into the body later. This procedure is not recommended for carriers of the BRCA genetic mutation due to their ovarian cancer risk. The success rate with this is low so far and it is not currently publicly funded in New Zealand.

GnRH agonists
In this method, gonadotropin-releasing hormone agonists are used to suppress ovarian function during chemotherapy, protecting the ovaries. Data regarding the effectiveness of this option is unclear. Research has shown that this can be effective in preserving fertility for some premenopausal women during chemotherapy for hormone receptor-negative breast cancer, but recent studies have been inconclusive.

It’s important to discuss fertility preservation with your specialist team as soon as possible after diagnosis so that an early referral to a fertility specialist can be arranged. Women can be seen within 1-2 days of referral and there are clinics in Auckland, Hamilton, Wellington, Christchurch and Dunedin.

Fertility after treatment is finished

Periods can come back 12-18 months after chemotherapy. Even if your periods haven’t started again it is still possible you are producing eggs and could become pregnant.

If your periods have returned, it's still possible that your ovaries may have been damaged during treatment and your fertility could be impacted.

Your specialist can check on your post-treatment fertility through blood tests and/or ultrasound. However, the results are not always reliable if you are taking adjuvant hormonal treatments for breast cancer.

If your ovaries have been affected and you cannot produce eggs, egg donation may be an option. Once again, this requires careful discussion with your specialist. Two cycles of this treatment are funded for menopausal women under age of 40.

In general, women are advised to wait at least two years post-treatment before considering pregnancy (this is due to the potential for early cancer recurrence). Data in this area is limited but there seems to be no increase in the risk of breast cancer recurrence with pregnancy. There is no evidence indicating that treatments can harm children conceived after treatment is finished.

It's important to discuss potential pregnancy plans with your specialist.

Contraception during treatment

Your specialist will advise you not to become pregnant while receiving treatment for breast cancer. These treatments can damage the ovaries and your eggs, and could harm a baby conceived during this time. You may also be advised to discontinue oral contraceptives following your diagnosis, as the hormones in the pill could stimulate growth of breast cancer cells. The use of condoms, diaphragm or non-hormone secreting IUD are all options to discuss with your specialist.

Talking to your specialist about fertility options

If you’re concerned about your fertility, here are some tips that might help those discussions:

Is my prognosis excellent, good, or poor?

How is treatment likely to affect my fertility?

Could I have children in the future? When would it be safe for me to become pregnant?

Fertility preservation: Which option is best for me? Which carries the least/most risk for me? Are the hormones in IVF treatment safe for me?

What are my options time-wise and cost-wise? How much time/delay is associated with each option and what are the costs?

Postponing treatment to allow time for fertility preservation: Would this be safe for me?